<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        let num1
        let num2
        function changeNum(num1, num2) {
            let among
            among = num1
            num1 = num2
            num2 = among
            return `交换后的结果是${num1}和${num2}`
        }
        num1=prompt(`请输入第一个数`)
        num2=prompt(`请输入第二个数`)
        let change = changeNum(num1, num2)
        document.write(change)
        let c=changeNum('chun','fu')
        document.write(c)
    </script>
</body>

</html>